This invention relates to the manufacturing method of a vacuum micro device having an electron emission type cold cathode.
The electron emission type vacuum micro device can be a self-emission type display with high-definition, which can attain better high-speed responsibility, better radiation resistance, and better heat resistance, in comparing with the conventional device, and thus has been actively studied in recent years.
The emitters of the vacuum micro device are formed from a material having small electron affinity. For example, the electron affinity of diamond has been found to be almost 0 by the recent study (J. Van et al.: J. Vac. Sci. Technol. B, 10, 4 [1992]), and plenty of studies have been dedicated to the manufacturing methods of the vacuum micro device having emitters formed from diamond.
One (V. V. Zhiron: J. Vac. Sci. Technol. B13(2), March/April: 1995) of the studies proposes a method wherein on a Si substrate, the base of each of the emitters is processed to form columns each having a height of 100 .mu.m and a diameter of several .mu.m, and a Si--Au alloy is formed at the tip of the column, and then the tip is sharpened by an etching or oxidation technique.
According to this method, the sharpened Si emitter tips are then coated with diamond. The diamond-coated emitters formed in this manner are, however, less stable and reliable since the Si emitter tips are not uniformly coated with diamond.
The diamond emitter has been also formed by another method: (1) by coating a conical conductor (e.g. Mo) with diamond; and (2) by filling a tip type mold formed in a Si substrate by the anisotoropic etching or the like with diamond.
According to the method (1), however, the coating of diamond is formed in particles and adhered to the conductor at random. The emitters formed in this manner have less stability and reproducibility in the emitter characteristics. While, according to the method (2), the shape of the diamond emitter can be attained with good reproducibility, but the Si substrate used for forming the tip type mold must be perfectly removed to expose the emitters after forming the diamond emitters. With such an additional step, the manufacturing cost of the device will increase.